


Something Smells Fishy

by Bunnyballs



Category: Shingeki no Kyojin | Attack on Titan
Genre: AU, Armin Arlert - Freeform, Mermaid Armin, One-Shots, Other, Reader-Insert, gender neutral reader, mermaid au
Language: English
Status: In-Progress
Published: 2017-01-26
Updated: 2017-04-16
Packaged: 2018-09-20 03:46:50
Rating: Not Rated
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 3,785
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/9473984
Author URL: https://archiveofourown.org/users/Bunnyballs/pseuds/Bunnyballs
Summary: The reader, who works at a small local fish store, finds a tiny merman with beautiful flowing fins among the shipment of bettas. Unable to get him all the way back home, reader gives up their own fish tank for the little betta fish merman to live in.Silliness, sweetness, etc ensues. There is bound to also be some sort of smut chapter knowing my disgusting self so stay tuned for that, along with various cute oneshots in this AU. Big thank you to my girlfriend Megan (Stardustmoth on here and stardust-moth on Tumblr) for helping me with this AU and with the editing on the fic. <3NOTE: This fanfiction is not fully accurate or all-involving real life facts about fish or fishkeeping, obviously. Please do proper research before buying or caring for any animal.





	1. Mermaids? In MY local fish store? It may be more likely than you think

This was not what you expected when you came into work this morning.

You were an employee at the small local fish shop. It was owned by a kind elderly man, and honestly wasn't much to speak of. The tiny store clung to the edge of a side-of-the-road shopping center, and not many people even noticed it existed. It was more of a way for the owner to share his hobby than an actual business, but you didn't mind. It was an easy job, you shared his hobby, and he was good to you. Every week a new shipment of various fish would come in and he usually entrusted you to their inspection and distribution into the store’s display tanks.

Usually, it was simple. Check for deaths on arrival, check for parasites or ill looking fish, put the bettas into their selling cups and acclimate the other fish to their tanks and add them throughout the day. Not today.

Rather, today you were frozen in place, hovering over the freshly opened shipment of male betta fish, staring into the face of what seemed to be a tiny human. You blinked hard a few times; surely it’s just your imagination. But there he is, the pale, minuscule figure of a person, floating groggily in a shipping bag. He choked wordlessly in fear as you picked up the bag. Initially you had thought that he was in the bag with another betta, but upon closer inspection you realized that the familiar shining, flowing fins were connected to his body. His tiny mouth and flawless, peachy lips were opened wide in shock, but his body seemed limp and his eyes half lidded as he struggled to flip his tail, a fruitless effort in the shallow shipping bag.

"Oh my God," you whispered, peering closer. His hair was a soft and silky looking blond, clinging to his face and neck wetly, two little blue fins peeking out on either side of his face like ears. As your eyes scanned lower you noticed his pale, flushed skin faded into beautiful blue scales that shone an iridescent turquoise in the right lighting. The iridescence streaked into the pale yellow and blue of his fins, which were currently clamped tightly to his body in sheer stress. You would have to figure out what type of tail he had later, after he calmed down you assumed.

Finally snapping out of your trance, you gasped, realizing you had been staring as this poor creature cowered in your hand. "Oh! Oh, my God! I'm not going to hurt you, I promise, don’t worry!" You placed him ever so gingerly on the counter, pouring some prepared water into a betta cup - He was only a bit larger than one, anyways. Once that was done you quickly but carefully cut his bag open, pouring out the water and sedative mixture he was shipped in before plopping him into the cup as gently as you could in your panicked state.

It all happened far too quick for the little creature to process in his medicated, hazy state, having put up no fight and sitting there quietly in his cup for a moment after. He seemed to notice the change though and dunked himself under the water of the cup, gasping softly with his mouth wide open. Did he just... 'yawn' like a betta? Regardless, he seemed refreshed by it. His thin little arms slipped out to hang off the edge of the cup as he resurfaced and stared up at you. You could've sworn you were dreaming when he opened his mouth and began to speak in a soft, timid tone. "Y-You really... Won't hurt me...?"

"No, I just... No. I won’t hurt you. I… don't even know what's happening." At least you were honest. There was a long pause after that comment, the little merman still groggy from the sedative.

"I'd like to know what's going on, too,” his small voice piped up, “I see you things all the time at home, but none of you have ever actually caught me... Where am I? What happened?" Despite his confused words, he didn’t seem too panicked about the situation. His little hands went to work at what seemed to be fluffing out his fins, still clamped tightly to his body but regaining their color a bit now.

"I… I don't know! I'm not even sure what you are! I'm a human and you're a... A tiny mermaid? A tiny mermaid! ...Oh God, wait, did you come from the ocean? Do you need salt water? I'm so sorry, I'll get you salt water, I'm so sorry for putting you in freshwater--"

"It's fine... This water is fine. I don’t even know what the ocean is… I live near a… a rice paddy, that's what it's called... How did you get me here? Why… am I so tired? Can I go home?" His hands continued to work at untangling his hair and splashing water onto his body, completely soaking himself. He seemed more curious now than afraid.

"Rice paddies are in Asia where bettas come from." was all you could blurt out, crouching lower and craning your neck to watch him closer in sheer awe. Before he could open his mouth to ask about Asia, which you assumed he had no knowledge of either, you added: "Asia is… far away from us right now, and um… I can't even explain it to you if you don't know what the ocean is, so... Well, it’s really far. Uh, we give fish medicine to calm them down before they travel long distances. Looks like you got dosed with it too, but don’t worry, it will wear off in an hour or so I think..."

"Why did take me here?" he asked, his large, doe-like blue eyes staring up at you. "Usually you things don't even bother touching me... I don’t understand."

You gulped. "We didn't mean to take you... But I don't think we can make up for it. I don't know what to do, I'm sorry."

The color in his fins paled again as another voice paired with footsteps interrupted the conversation, making you jump and rush to hide him. "Go under the water!" you begged of him as you got one of the lids out and began to firmly put it on his cup, then shoving it into your backpack. You would mark the missing 'fish' as being a death upon arrival. "Hello sir," you said weakly as your boss walked into the room, having been calling your name.

"Same greetings to you too, (Y/N)." He gave you a friendly smile as his eyes scanned the counter you'd been doing your work at. His facial expression changed to a more curious look. "Oh, my. You haven't got all the bettas in their cups yet? Is something wrong?"

You chuckled nervously, getting back to work. "No, I just had insomnia last night is all. And we had a nasty looking dead on arrival male. Sorry sir, I promise I'll have them all out within the next ten minutes."

"That's quite alright, I understand insomnia. Just tell me if you need to go home early after inspecting all the shipments, alright? You know I wouldn't make you work too hard while you're not well. And tell me if you want any of the fish held out back for you, I know you'd been aching to put something in your new tank and I know you'll take care of whatever you buy."

"Yessir," you replied with a smile, "Thank you so much for everything, sir. I'll be fine though, I promise!"

After that he went back to the front counter with another friendly smile and a nod directed towards you. It would be a long day with your mind on the little merman in your backpack. You just hoped he'd be okay in there until you could go home.

-  
After a long shift and a LONG talk on the ride home with the merman, who you had learned was named Armin, you finally carried him inside with a sigh. You had explained the situation to him as best you could, and he was unnaturally realistic about it. Depressed, but realistic and shockingly curious about the human world.

You had also explained to him that you had a home for him. You were kissing goodbye all the hard work you put into a deluxe 20-gallon freshwater tank for him. That would be his home now - Maybe you could slip a few fish in there if you convinced him enough though, even if just for the sake of not having your friends or family ask why you had an empty fish tank for so long when they came over and he would have to hide.

With those thoughts in mind you immediately threw your backpack on the floor once inside and began to set him up. Your tank was densely populated with live plants and natural, hollow driftwood, sand, and a few little stone caves here and there. You had chosen to stay away from plastic decorations much to your wallet's demise and your aesthetic's delight, but you couldn't have lost those regrets any faster. You wondered if the poor boy would have been insulted by fake plants and plastic rocks.

"It's not much, I'm sorry," you mumbled as he floated in his little cup, acclimating to the water temperature. You hadn't been looking at him as you said that, worried for his reaction that you assumed would be displeasure. Rather, he was amazed.

"This is all my home?! This is nothing like the muddy little puddles I'd jump between all day! What is this? What are those?" His hand gestured to just about everything as he began asking about it all, to which you replied the name of the plant, or about the wood, or the caves, or the filter. His eyes seemed to shine brightly as he listened, taking this much better than you'd have expected. Finally, though, he excitedly asked, "Why am I just floating here when I could be in there?"

Before you could stop him, he jumped over the cup's edge with ease, the sedative having clearly worn off, and gracefully dove into the tank before bobbing to the surface. "This water feels great, thank you so much! ...Why do you look so pale?"

"...Don’t you need temperature acclamation?! Am I treating you too much like a fish? I'm sorry, I just thought..." You let that sentence trail off before you embarrassed yourself more. You just wanted to try your best with what knowledge you had, but you also didn't want to dehumanize this very humanized creature.

"I in fact do not!" he chirped, having no sign of offense taken. "I'm not a fish, but that's okay. I mean, you've told me you've never met a mermaid before... And we are kind of similar, obviously. I'm just so thankful that you're trying your best to help me even though it wasn't you who wronged me. You're just a store employee... I'm sorry that I have to rely on you like this, I promise I'll try to make it up to you. I just don't know where I can go when I'm so far from home and what I know..." He frowned slightly, his head slowly bowing as the realization hit him again. "Thank you again."

"It's fine," you replied softly. " I know this is a crazy situation that none of us expected to happen, and I can't just leave somebody in a bag in peril. You don't have to make it up to me… Though, we're both going to have to get used to some things."

Armin tilted his head. "Like what?"

"Well," you replied, "...I'm going to have to put my hands in your home a lot for maintenance… and sometimes I get visitors, and we can’t have them see you. But I'm sure you don't want to hear about rules right now, we can get you some food first. Are you hungry?"

You didn't expect a such a loud, enthusiastic "Yes please!" from such a small creature. "I didn't eat for two days in that bag - I think. I don't know, it was dark and I was doused in that drowsy stuff..."

"So, what do you ea--" You paused. Armin had fallen silent. He was suddenly staring up with such vigilance and determination on his face that you stopped too, watching his body stiffen but his eyes zip around from side to side quickly. "What's wrong?" you asked after a moment, only to be met with no response.

Another moment of silence and worry taking over your head.

_Sploosh!_

Before you could register what happened Armin was already falling back into the tank, having jumped far over the water's surface for something that was now in his hands. You wordlessly watched him rip something from it, then resurface along with what looked like a pair of transparent, flaky ovals in his other little fist. He was now smiling at you and fluttering out his fins happily. "Oh, did I scare you? Sorry," he giggled, "But you have to catch prey while you can!"

"...What? What did you catch?"

"A fruit fly!" he chirped, obviously proud of himself. Your stomach turned a bit as you watched him bite it in half, realizing that what he had ripped of was its wings. Of course. Bettas mostly eat bugs and their larvae in the wild... Perhaps you would move your bowl of fruit from the kitchen counter over to the stand beside his tank to keep them off your bananas, you thought, even though it was a bit disgusting to watch a tiny human face bite into a fruit fly right in front of you. Thankfully, it was gone in mere moments and he was already licking his lips and wiping them clean with the back of his hand. "...Can I ask for some more, please?"

"Uh. I don't know if I have any more but I can try to lure them to you... I... Guess..."

It was official now.

You would both definitely have to get used to some more-than-eccentric things about each others' lives.


	2. VACUUM of DEATH

**Summary for the Chapter:**

> Oh? Oh you thought it would all be cute and funny? That's very cute of you but I'm putting in a few sad bits that will tie into this later. YOU THOUGHT.
> 
> Also 'disks' are him mishearing 'discus' for anybody wondering, lol

It was finally the day. The dreaded day you knew Armin would hate, so many things could go wrong with his curiosity.

Tank cleaning day.

It had been roughly a week since the tank’s last change, maybe a day or two past because you had been dreading it with Armin there now. You knew that changing the empty, cycling tank would be easier than this. You just didn’t want to scare or hurt the poor little guy. You sucked in a deep breath, and set a bucket and towel down next to the tank. “Hey Armin.”

Armin quickly noticed you by his little home trying to get his attention, swimming up to the rim of the tank and grasping onto it. “Hey Y/N! What’s with that tense look? And bucket?” Before anything was said he began to get a bit nervous, lowering himself so that only his grasping fingers and eyes peeked above the tank rim. “B-Buy some new fish or something?” _‘They had better not have been those big fish I saw in the back of the store while we were still there,’_ he thought. _‘What were those called… Disks?’_

His reaction softened you up a bit, earning an actual laugh from you. “No, I wouldn’t do that to you without talking about it first. Remember how I said I would have to get in there and do maintenance a lot? I have to take out some of the water and vacuum the nasties out of the sand with this thing.” You held up your siphon for him to see, briefly explaining it to him which earned a few ‘ooh’s and ‘aah’s. You were glad to see that at least the idea didn’t scare him off or make him become defensive at the very least, but you still had a creeping feeling that he wouldn’t like it or that something would go wrong.

By the time you were done explaining he has his elbows on the rim, chin laying on his crossed arms. His eyes held both curiosity and slight nervousness, most likely from the fact that it was still all new to him. “Okay… So, what do I do while you do this?”

You shrugged. “Anything you want to, really. Just try to keep your fins away from the vacuum or you could get hurt, okay? If this is too stressful for you I can just take you out at any time and put you in another container, just tell me.”

“Okay…”

You gave him a reassuring smile. “Okay.” And with that, you began starting the siphon up, explaining a bit more as you went. “Now the suction is started, see? Try and be careful, I don’t want you hurt!” You began doing your work, continuing to tell him all about the _wonders_ of cleaning a dirty fish tank and all it entailed to keep these, in his words, ‘magical’ boxes of water safely running.

Armin seemed both intrigued and disgusted as he watched all the gunk he created being sucked up. “So it would be safe to swim near it so long as my fins aren’t too close? I just really want to see it, it’s so weird to me…”

“I mean, it should be. Just be careful. I’m going to keep my other hand on the hose so I can kink it and stop the flow if anything happens, so don’t worry about it.” You watched as he ducked underneath the water and swam up to it slowly with his arms held out, inspecting the flow from a distance that way. He looked over to you and smiled, inching closer and closer. You smiled back which in turn made his own grow, the two of you getting lost in the playfulness and simple joy of the moment.

You almost wished you hadn’t.

A mere second later and Armin’s smile turned to horror, his mouth opening to scream that you could barely hear through the water muffling it. His face was enough to say something was wrong though, and you pried your eyes away from it to notice his arm, then in turn the rest of him being greedily sucked into the siphon intake.

With a screech of your own you kinked the hose attached to the tool, stopping the flow and suction immediately. Armin began sinking to the bottom as stiff as a log as soon as its pull stopped, eyes wide and fins nearly completely transparent. You dropped the siphon and left it hanging over the edge of the tank to the side, dipping your arms in to catch and cradle the poor boy. “Are you okay?!”

He didn’t respond the first time. “Armin! Hey, can you hear me?” After hearing his name and feeling your gently cradling hands lift him above the water, he finally shook his head and looked up to you, blinking a few times.

“…Yes.” He muttered, as if in trance. “I’m okay… I just got startled…” He seemed a tiny bit less okay than he wanted you to believe, but at least some of his color was coming back slowly and he was coming out of his startled trance. “I-I’m okay.” He said in a watery voice, swallowing thickly.

You frowned, dipping his lower half back into the water in case he wanted to go back in the tank now. “Are you sure?”

He gave a pitiful sniffle, one that was barely, just barely audible. “Yes. I just got scared for a moment.” Even as he said that tiny tears began to accumulate in the corners of his eyes, running down his already damp cheeks as the droplets became too much of a weight for his thick lashes to handle.

You flinched as you watched this beautiful, tiny creature weep softly in the palms of your hands, leaning closer to try to seem more personable and closing up your hands a bit more to make him feel sheltered. “Armin—What’s the matter? Really, you can tell me, did I hurt you? Please, tell me...”

He flopped over towards one of your thumbs, hugging it closely like you often saw him do to some more delicate plant leaves when sleepy. Your thumb was like a body pillow to him in relative size, soft and warm and comforting against him as he curled his tail up closer to his body. “It felt like it was trying to eat me,” he sniffled, obviously trying to hide what was going on but failing miserably, “I have to fight for my life at times in the wild and I thought I was going to die for a moment and I’m sorry, I’m so used to almost dying when that sort of thing happens and it’s a lot of emotions…”

You gave him a pitying look and rubbed your other thumb across his back comfortingly, dropping your voice to a whisper. “Hey, I’m sorry. We can take you out of the tank before I do this next time, okay? You can stay in my hands for as long as you want to. I’m sure it must be terrifying and emotional to almost die. I thought you would weigh enough that it wouldn’t pull you in, I’m so sorry.”

It got very quiet for a few moments after that, but surely he began to calm down in your hands and looked up at you with red, puffy eyes. “Please ignore what just happened, I’m sure it must seem ridiculous. But maybe I’ll tell you the full story later… This may even just be all the stress of the whole situation weighing on me, I usually don’t _cry_ over it...”

“Hey, it’s fine. Really. I can’t even imagine what you must go through on a daily basis back home, or how much you must miss everybody there. It’s okay, I don’t mind it.” Something sparked inside of you that you hadn’t felt in a while. Something caring and soft, almost parental. “Hey… You wanna like… Stay close for a while?”

A mix of humiliation, shame, and hope swirled in the expression of his eyes. “Can I?”

Not caring that your hand was wet, you pulled it away from the merman for a moment to grab the lamp on the stand next to the tank, and place it on the floor, then taking a seat on the stand and scooping your hand back under Armin only for him to wiggle onto it again.

“Of course you can. I’m here for you now.”


End file.
